Radiation thermometer

ABSTRACT

The radiation clinical thermometer of the present invention is provided with a light guide tube 15 to guide the infrared radiation from the temperature-measured object, a first infrared sensor 10 for detecting the infrared radiation from the light guide tube 15, a temperature sensitive sensor 12 which generates a reference temperature signal, a reference cavity 17 which has approximately the same temperature condition as the light guide tube 15 and is sealed so as to shut out infrared radiation from outside, a second infrared sensor 11 for detecting the infrared radiation from the reference cavity 17, a temperature computing means 13 for calculating temperature in accordance with the signals from the first infrared sensor 10 and the second infrared sensor 11, a temperature sensitive sensor 12, and a display unit 14 for displaying temperature in accordance with the signal from the temperature computing means 13; and at least either the light guide tube 15 or the reference cavity 17 is tapered off toward the emission inlet of the light guide tube 15 from the first or second infrared sensor 10 or 11 side.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a radiation clinical thermometer whichdetects thermal radiation energy to measure temperature without contact.

RELATED ARTS

To measure body temperature in a short period of time, a radiationclinical thermometer which allows one to choose the eardrum formeasuring the temperature thereof without contacting the same has beensuggested.

For example, the present applicant proposed the radiation clinicalthermometer shown in FIGS. 10 and 11 in Japanese Patent ApplicationNo-Hei-7-294117. FIG. 10 is a front elevation view showing the radiationclinical thermometer proposed in Japanese Patent Application No.Hei-7-294117.

The radiation clinical thermometer 1 is a clinical thermometer designedto measure the temperature of the eardrum comprising a main body 4 and aprobe 2. The main body 4 is provided with a liquid crystal displayelement 6 for displaying the body temperature and a measurement switch 5of a push button structure.

The radiation clinical thermometer 1 operates as follows. First, themeasurement switch 5 is pressed to turn on the power for startingtemperature measurement, Subsequently, the probe 2 is inserted into themeatus auditorium externus of the subject to face the eardrum to measurethe temperature thereof. The probe 2 is oriented to the eardrum properlyand then the probe 2 is taken out of the meatus auditorium externus. Theliquid crystal display component 6 shows the maximum temperaturemeasured here, so that the temperature of the eardrum, that is, the bodytemperature, is displayed to allow one to read the display as the bodytemperature of the subject.

FIG. 11 is a partially cut-out cross-sectional view showing the probe 2of the radiation clinical thermometer shown in FIG. 10.

The probe 2 is provided, on the top-end thereof, with a filter 7 whichhas transmission wavelength characteristics. The dustproof filter 7 ismade from optical crystal such as silicon (Si) or barium fluoride (BaF₂)or a polymer such as polyethylene, and selectively transmitsinfrared-wavelength radiation.

A light guide tube 8 is a tube which is provided to efficiently convergethe thermal radiation from the eardrum the temperature of which is to bemeasured, made of metal pipes such as copper, brass, or stainless steel,and the inner surface of which is a mirror-finished surface coated withgold (Au) to increase the reflectivity. The application of the coating,however, will not allow the inner surface of the light guide tube 8 tobecome a perfect reflector having a reflective index of 1.00 and thuscause the inner surface of the light guide tube 8 to remain more or lessradiative.

A light guide tube 9 is made from the same material as the light guidetube 8 with the inner surface treated in the same way as the light guidetube 8 and one end (on the side of the filter 7) sealed so that infraredradiation cannot come in from the temperature-measured object. Inaddition, the light guide tube 9 is provided close to the light guidetube 8 so as to keep approximately the same temperature as the lightguide tube 8. The condition required for the light guide tube 9 is toreach approximately the same temperature as the light guide tube 8 butnot always necessarily to be the same in material or inner surfacecondition.

A first infrared sensor 10 detects the infrared radiation emitted by thetemperature-measured object and converged by the light guide tube 8, andalso detects the thermal radiation from the light guide tube 8 itself. Asecond infrared sensor 11 detects the thermal radiation from the lightguide tube 9 itself because the top-end of the light guide tube 9 issealed. In addition, the second infrared sensor 11 is provided close tothe first infrared sensor 10 so as to have approximately the sametemperature as the first infrared sensor 10. A temperature sensitivesensor 12 is a sensor which allows for measuring the temperature of thefirst infrared sensor 10 and the second infrared sensor 11.

The operation principle with the first and second infrared sensors 10and 11 is briefly explained here. If the light guide tube 8 and thefirst infrared sensor 10 are at the same temperature, the first infraredsensor 10 is allowed to apparently detect the infrared radiation onlyfrom the temperature-measured object. This is because the light guidetube 8 also gives off thermal radiation but has the same temperature asthe infrared sensor 10, so that the thermal radiation from the lightguide tube 8 is negligible when the difference in radiance and incidenceat the infrared sensor 10 is taken into account. A difference intemperature between the light guide tube 8 and the first infrared sensor10, however, develops a difference in thermal radiation between thelight guide tube 8 and the first infrared sensor 10 to cause the firstinfrared sensor 10 to detect the thermal radiation from thetemperature-measured object and the light guide tube 8 so that thethermal radiation from the light guide tube 8 is not negligible.

Therefore the known radiation clinical thermometer 1 is provided withthe second infrared sensor 11 to allow the second infrared sensor 11 todetect the infrared radiation from the light guide 9, which is heldunder the same temperature condition as the light guide tube 8, toreduce at an adequate proportion the output of the second infraredsensor 11 from the output of the first infrared sensor 10 which isaffected by the temperature of the light guide tube 8 to detect theinfrared radiation from the temperature-measured object, independent ofthe temperature effects of the light guide tube 8.

Another example of the prior arts is not a clinical thermometer but aradiation thermometer which is disclosed in Japanese Laid-open PatentPublication No. Sho-61-66131.

This radiation thermometer is provided with a signal fiber which guidesthe infrared radiation from the temperature-measured object andcorresponds to the light guide tube 8 of the radiation clinicalthermometer proposed in Japanese Patent Application No. Hei-7-294117,and with a disturbance fiber corresponding to the light guide tube 9 toeliminate the effects of disturbance for measuring temperature.

There exists the problem, however, that providing two light guide tubesor fibers as conventionally done causes the diameter of the top-end forfacing to the temperature-measured object, that is, the probe, to becomelarger to accommodate two or more light guide tubes or fibers.

Especially for a radiation clinical thermometer which is inserted intothe meatus auditorius externus to detect the infrared radiation from theeardrum, there exists a problem that a radiation clinical thermometerwith a probe of a large diameter has difficulty in inserting theradiation clinical thermometer into the meatus auditorium externus toface to the eardrum of a child whose ear hole is small.

To overcome this problem, it may be considered to make the two lightguide tubes etc. thinner, however, this causes the emission outlet ofthe light guide tubes to become smaller and also the original view ofthe infrared sensor to become smaller due to the emission outlet.Additionally this causes the incident energy to decrease to lead to adecrease in sensitivity. Generally, making the view narrower tends tolead to decreasing the incident energy. And also a thin light guide tubeetc. causes the number of reflections of infrared radiation inside thelight guide tube to increase. Taking into account that energy is lost atevery reflection, sensitivity is disadvantageously affected in thispoint.

DISCLOSURE OF THE INVENTION

The present invention is for purposes of the foregoing to provide aradiation clinical thermometer having a top-end, that is, a probe, forfacing the temperature-measured object made thinner without reducingsensitivity.

To achieve the foregoing purposes, the present invention is providedwith a light guide means having an emission inlet and an emission outletto guide the infrared radiation from the temperature-measured object, afirst infrared sensor for detecting the infrared radiation from thelight guide means, a temperature sensitive sensor which generates areference temperature signal, a reference cavity which has approximatelythe same temperature condition as said light guide means and is sealedso as to shut out infrared radiation from outside, a second infraredsensor for detecting the infrared radiation from the reference cavity, atemperature computing means for calculating temperature in accordancewith the signals from said first infrared sensor and said secondinfrared sensor, and said temperature sensitive sensor, and a displayunit for displaying temperature in accordance with the signal from thetemperature computing means; and the probe is provided on the insidethereof with said light guide means and said reference cavity, at leasteither said light guide means or said reference cavity being taperedtoward the emission inlet from said first or second infrared sensor.

In one form of the invention the light guide means comprises a pipe andsaid reference cavity comprises a supporting member which supports saidpipe.

Furthermore the invention contemplates that the light guide meanscomprises a pipe and the reference cavity comprises the outer wall ofsaid pipe and the supporting member which supports said pipe.

In one form of the invention the supporting member comprises a member ofhigh thermal conductivity, such as aluminum.

Another aspect of the invention provides that the first infrared sensorand the second infrared sensor are arranged in parallel to each otheracross the center of said probe, and the emission inlet of said pipe ispositioned approximately at the center of said probe and the emissionoutlet is positioned toward said first infrared sensor, whereby the pipeis positioned diagonally against the center line of said probe.

In one embodiment of the invention the first infrared sensor ispositioned on the center line of said probe and said pipe is positionedalong said center line.

According to other aspects of the invention the light guide means andsaid reference cavity are formed into the same member in one piece; thetemperature sensitive sensor is adhered to the bottom surface of thefirst infrared sensor or second infrared sensor by adhesive; a windowmember for transmitting infrared radiation is fitted to the probe so asto seal the emission inlet of said light guide means; the window memberfor transmitting infrared radiation can be fitted to said pipe so as toseal the emission inlet of said light guide means, or the window memberfor transmitting infrared radiation can be fitted to the supportingmember for sealing the emission inlet of the light guide means.

According to the invention the reference cavity is tapered toward theemission inlet of the light guide means from the second infrared sensorwithout reducing sensitivity, so that a radiation clinical thermometerwhich has a thin top-end, that is, a probe, for facingtemperature-measured objects can be provided. Furthermore, even in thecase where the light guide means is tapered toward the emission inlet ofthe light guide means from the first infrared sensor side, a radiationclinical thermometer having a thin probe can be provided. Furthermore,compared with the conventional thermometer having two light guide tubes,a lesser number of light guide tubes allows for producing a cheaperradiation clinical thermometer.

Furthermore, tapering off the probe to the top-end allows in turn theemission outlet to broaden, whereby the area of the infrared sensor canbe enlarged. An infrared sensor of a larger area allows for making theinfrared sensor highly sensitive and thus providing a radiation clinicalthermometer having a simple amplifier with less noise.

The invention has the effect that the reference cavity is formed only bythe supporting member, whereby no space is available for allowinginfrared radiation to come into the reference cavity from outside andthus infrared radiation from outside can be positively shut out.

Furthermore the invention has the effect that the reference cavity isformed by the supporting member and the outer wall of the light guidetube, whereby the reference cavity easily reflects the temperature ofthe light guide tube.

Another effect of the invention is that the light guide means and thereference cavity can be easily held to approximately the sametemperature Additionally, in the case where a difference in temperatureis developed between the light guide means and the infrared sensor, theeffect that the light guide means and the infrared sensor reach anequilibrium state sooner is also given.

Furthermore the invention has the effect that aluminum has a goodthermal conductivity and also allows for forming a supporting member ofa complicated shape by aluminum die-casting.

Other effects of the invention are that a thinner probe can be made;that the center axis of the supporting member is the same as the centeraxis of the hole for inserting a pipe as the light guide tube, wherebythe hole of the supporting member can be easily and accurately finishedby cutting; that the use of a pipe as the light guide tube is notnecessary so that costs can be saved; that the temperature of the sealedsensor can be measured with greater accuracy; that the filter canprevent water from coming into the probe; that the filter reaches thesame temperature as the light guide tube, so that the body temperaturecan be measured more accurately; and/or that in the event the filter isfitted to the supporting member, the filter reaches approximately thesame temperature as the supporting member (the light guide means by alight guide hole), so that the body temperature can be measured moreaccurately.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut-out cross-section view showing the probe ofthe first embodiment of the radiation clinical thermometer in accordancewith the present invention;

FIG. 2 is an explanatory block diagram showing the operation of theradiation clinical thermometer shown in FIG. 1;

FIG. 3 is a partially cut-out cross-section view showing the probe ofthe second embodiment of the radiation clinical thermometer inaccordance with the present invention;

FIG. 4A is a cross-section view taken on line A-A' of FIG. 3, FIG. 4Bbeing a cross-section view taken on line B-B' of FIG. 3, and FIG. 4Cbeing a cross-section view taken on line C-C' of FIG. 3;

FIG. 5 is a partially cut-out cross-section view showing the probe ofthe third embodiment of the radiation clinical thermometer in accordancewith the present invention;

FIG. 6 is a partially cut-out cross-section view showing the probe ofthe fourth embodiment of the radiation clinical thermometer inaccordance with the present invention;

FIG. 7 is a partially cut-out cross-section view showing the probe ofthe fifth embodiment of the radiation clinical thermometer in accordancewith the present invention;

FIG. 8 is a partially cut-out cross-section view showing the probe ofthe sixth embodiment of the radiation clinical thermometer in accordancewith the present invention;

FIG. 9 is an explanatory view showing an example of the shape of thereference cavity of the radiation clinical thermometer in accordancewith the present invention;

FIG. 10 is a front elevation view showing the radiation clinicalthermometer suggested in Japanese Patent Application No. Hei-7-294117;and

FIG. 11 is a partially cut-out cross-section view showing the probe 2 ofthe radiation clinical thermometer 1 shown in FIG. 10.

PREFERRED EMBODIMENTS OF THE INVENTION

The present invention is described below in accordance with thedrawings.

It is to be understood that the elevation front view of the radiationclinical thermometer in accordance with the present invention is almostthe same as FIG. 10, so that explanation on the following embodiments ofthe present invention is carried out referring to FIG. 10.

FIG. 1 is a partially cut-out cross-section view showing the probe ofthe first embodiment of the radiation clinical thermometer in accordancewith the present invention. The material of the probe 2 is, for example,ABS resin, and the probe 2 is provided inside with the light guide tube15 and supporting member 16.

The light guide tube is a pipe which is provided to efficiently convergethe thermal radiation from the eardrum the temperature of which is to bemeasured, made of metal such as copper, brass, or stainless steel, andthe inner surface of which is a mirror-finished surface coated with gold(Au) to increase the reflectivity.

The light guide tube 15 is provided on the top-end thereof with thefilter 7 having transmission wavelength characteristics The filter 7, adustproof window member for transmitting infrared radiation, is formedby optical crystal such as silicon (Si) or barium fluoride (BaF₂), or apolymer such as polyethylene, and selectively transmitsinfrared-wavelength radiation. The light guide tube 15 is cut diagonallyat the top-end thereof so that the filter 7 fitted to the top-end of thelight guide tube 15 is positioned perpendicular to the center line ofthe probe.

The supporting member 16, which is a member for supporting the lightguide tube 15 inside the probe 2, has the shape shown in FIG. 1 to formthe reference cavity 17 which serves as the light guide tube 9 in FIG.11. The supporting member 16 is a member of high thermal conductivity,the material of which is, for example, aluminum. The reference cavity 17is sealed at the one end thereof (on the side of filter 7) so as toprevent infrared radiation from coming in from the temperature-measuredobject. In addition, the reference cavity 17 is provided close to thelight guide tube 15 to become approximately the same temperature as thelight guide tube 15. The condition required for the reference cavity 17is to reach approximately the same temperature as the light guide tube15 but is not always necessarily the same in material or inner surfacecondition. Furthermore the reference cavity 17 is so constructed as tobe tapered toward the emission inlet 15a from the second infrared sensor11.

Infrared sensor 10 detects the infrared radiation emitted by thetemperature-measured object and converged by the light guide tube 15,and also detects the thermal radiation from the light guide tube 15itself. A second infrared sensor 11 detects the thermal radiation fromthe reference cavity 17 itself because the top-end of the referencecavity 17 is sealed. In addition, the second infrared sensor 11 isprovided close to the first infrared sensor 10 so as to haveapproximately the same temperature as the first infrared sensor 10. Atemperature sensitive sensor 12 is a sensor which allows for measuringthe temperature of the first infrared sensor 10 and the second infraredsensor 11. Therefore the temperature sensitive sensor 12 is preferablyfixed to the bottom surface of the first infrared sensor 10 or thesecond infrared sensor 11, for example, by adhesive 12a. An adhesive ofhigh thermal conductivity may be preferably selected (for example,silicone of high thermal conductivity) for the adhesive 12a.

Furthermore the first infrared sensor 10 and the second infrared sensor11 are arranged in parallel to each other across the center of the probe2, and the emission inlet 15a of the light guide tube 15 is positionedapproximately at the center of the probe 2 and the emission outlet 15bis positioned toward the first infrared sensor 10, whereby the lightguide tube 15 is positioned diagonally against the center line of theprobe 2.

FIG. 2 is an explanatory block diagram showing the operation of theradiation clinical thermometer shown in FIG. 1. It is to be understoodthat, in FIG. 2, those parts that are the same as in FIG. 1 are given bythe same reference numbers.

The operation of the first and second infrared sensors 10 and 11 willnow be briefly explained. If the light guide tube 15 and the firstinfrared sensor 10 are at the same temperature, the first infraredsensor 10 is allowed to apparently detect the infrared radiation onlyfrom the temperature-measured object. This is because the light guidetube 15 also gives off thermal radiation but has the same temperature asthe infrared sensor 10, so that the thermal radiation from the lightguide tube 15 is negligible when the difference in radiance andincidence at the infrared sensor 10 is taken into account. A differencein temperature between the light guide tube 15 and the first infraredsensor 10, however, develops a difference in thermal radiation betweenthe light guide tube 15 and the first infrared sensor 10 to cause thefirst infrared sensor 10 to detect the thermal radiation from thetemperature-measured object and the light guide tube 15 so that thethermal radiation from the light guide tube 15 is not negligible.

Therefore the radiation clinical thermometer of the present invention isprovided with the second infrared sensor 11 to detect the infraredradiation from the reference cavity 17, which is held under the sametemperature condition as the light guide tube 15, to reduce at anadequate proportion the output of the second infrared sensor 11 from theoutput of the first infrared sensor 10 which is affected by thetemperature of the light guide tube 15 to detect the infrared radiationfrom the temperature-measured object, independent of the temperatureeffects of the light guide tube 15. The temperature computing means 13calculates the temperature of the temperature-measured object inaccordance with the outputs from the first infrared sensor 10, thesecond infrared sensor 11, and the temperature sensitive sensor 12, anddisplays the temperature on the display unit 14.

FIG. 3 is a partially cut-out cross-section view showing the probe ofthe second embodiment of the radiation clinical thermometer inaccordance with the present intention.

The material of the probe 2 is, for example, ABS resin, and the probe 2is provided inside with the light guide tube is and supporting member19.

The light guide tube 18 is a pipe to efficiently converge the thermalradiation from the eardrum the temperature of which is to be measured,is made of metal such as copper, brass, or stainless steel, and has aninner surface which is mirror-finished and coated with gold (Au) toincrease the reflectivity.

The probe 2 is provided on the top-end thereof with the filter 7 hatingtransmission wavelength characteristics. The filter 7, a dustproofwindow member for transmitting infrared radiation, is formed by opticalcrystal such as silicon (Si) or barium fluoride (BaF₂), or a polymersuch as polyethylene, and selectively transmits infrared-wavelengthradiation. In this embodiment, the filter 7 is provided not on thetop-end of the light guide tube 18 but on the top-end of the probe 2, sothat the top-end of the light guide tube 18 is not required to be cutdiagonally.

The supporting member 19, which is a member for supporting the lightguide tube 19 inside the probe 2, has the shape shown in FIG. 3 to formthe reference cavity 20 which serves as the light guide tube 9 in FIG.11. The supporting member 19 is a member of high thermal conductivity,the material of which is, for example, aluminum. The reference cavity 20of this embodiment comprises the supporting member 19 and the outer wallof the light guide tube 18, and is sealed at the one end thereof (on theside of filter 7) so as to prevent infrared radiation from coming infrom the temperature-measured object Additionally, the outer wall of thelight guide tube 18 constitutes a part of the reference cavity 20, sothat the inner wall of the reference cavity 20 approximates the sametemperature as the inner wall of the light guide tube 18. The conditionrequired for the reference cavity 20 is to reach almost the sametemperature as the light guide tube 18 but is not always necessarily thesame in material or inner surface condition. Furthermore the referencecavity 20 is so constructed as to be tapered toward the filter 7 sidefrom the second infrared sensor 11 side.

Infrared sensor 10 detects the infrared radiation emitted by thetemperature-measured object and converged by the light guide tube 18,and also detects the thermal radiation from the light guide tube 18itself. The second infrared sensor 11 detects the thermal radiation fromthe reference cavity 20 itself because the top-end of the referencecavity 20 is sealed. In addition, the second infrared sensor 11 isprovided close to the first infrared sensor 10 so as to haveapproximately the same temperature as the first infrared sensor 10. Thetemperature sensitive sensor 12 is a sensor which allows for measuringthe temperature of the first infrared sensor 10 and the second infraredsensor 11. Therefore the temperature sensitive sensor 12 is preferablyfixed to the bottom surface of the first infrared sensor 10 or thesecond infrared sensor 11, for example, by adhesive 12a. An adhesive ofhigh thermal conductivity may be preferably selected (for example,silicone of high thermal conductivity) as the adhesive 12a.

Furthermore the first infrared sensor 10 and the second infrared sensor11 are arranged in parallel to each other across the center of the probe2, and the emission inlet 18a of the light guide tube 18 is positionedapproximately at the center of the probe 2 and the emission outlet 18bis positioned toward the first infrared sensor 10, whereby the lightguide tube 18 is positioned diagonally against the center line of theprobe 2.

Furthermore, in this embodiment, the first infrared sensor 10 and thesecond infrared sensor 11 are sealed with cover 21 which adheres thewindow member with low melting-point glass to receive infrared radiationthrough the windows 22 and 23. The windows 22 and 23 are made frombarium fluoride (BaF₂) or silicon (Si) with anti-reflection coating (ARcoating). Nitrogen gas is sealed in the room enclosed with the cover 21to prevent the first infrared sensor 10 and the second infrared sensor11 from being deteriorated.

It is to be understood that the operation of the radiation clinicalthermometer of this embodiment is the same as the first embodiment shownin FIG. 1 and, for this reason, an explanation is omitted here.

FIG. 4 are cross-sectional views of the radiation clinical thermometershown in FIG. 3; FIG. 4A is a cross-section view taken on line A-A' ofFIG. 3; FIG. 4B is a cross-section view taken on line B-B' of FIG. 3;and FIG. 4C is a cross-section view taken on line C-C' of FIG. 3. Ineach cross-section view, only the light guide tube 18, the supportingmember 19, and the reference cavity 20 are illustrated.

It is to be clearly understood that the outer wall of the light guidetube 18 constitutes a part of the inner wall of the reference cavity 20and the reference cavity 20 is tapered toward the filter 7 from thefirst infrared sensor 10.

FIG. 5 is a partially cut-out cross-section view showing the probe ofthe third embodiment of the radiation clinical thermometer in accordancewith the present invention. The material of the probe 2 is, for example,ABS resin, and the probe 2 is provided inside the same with the lightguide tube 24 and supporting member 25.

The light guide tube 24 is a pipe which is provided to efficientlyconverge the thermal radiation from the eardrum the temperature of whichis to be measured, is made of metal such as copper, brass, or stainlesssteel, and has an inner surface which is mirror-finished and coated withgold (Au) to increase the reflectivity.

The probe 2 is provided on the top-end thereof with the filter 7 havingtransmission wavelength characteristics. The filter 7, a dustproofwindow member for transmitting infrared radiation, is formed by opticalcrystal such as silicon (Si) or barium fluoride (BaF₂), or a polymersuch as polyethylene, and effectively transmits infrared-wavelengthradiation.

The supporting member 25, which is a member for supporting the lightguide tube 24 inside the probe 2, has the shape shown in FIG. 5 to formthe reference cavity 26 which serves as the light guide tube 9 in FIG.11. The supporting member 25 is a member of high thermal conductivity,the material of which is, for example, aluminum. The reference cavity 26of this embodiment comprises the supporting member 25 and the outer wallof the light guide tube 24, and the reference cavity 26 is sealed at theone,end thereof (on the side of filter 7) so as to prevent infraredradiation from coming in from the temperature-measured object.Additionally the outer wall of the light guide tube 24 constitutes apart of the reference cavity 26, so that the inner wall of the referencecavity 26 has approximately the same temperature as the inner wall ofthe light guide tube 24. The reference cavity 26 is to reach almost thesame temperature as the light guide tube 24 but is not alwaysnecessarily the same in material or inner surface condition. Furthermorethe reference cavity 26 is so constructed as to be tapered toward thefilter 7 side from the second infrared sensor 11 side.

This embodiment, as is understood,by comparing FIG. 3 with FIG. 5, ischaracterized in that the light guide tube 24 is provided perpendicularto the filter 7 and the first infrared sensor 10. That is, the firstinfrared sensor 10 is positioned on the center line of the probe 2 andthe light guide tube 24 is positioned along the center line of the probe2, whereby the diameter of the probe 2 is made a little larger comparedwith the embodiment shown in FIG. 3. However, the center axis of thesupporting member 25 is the same as the center axis of the hole forinserting a pipe as the light guide tube 24, whereby the hole of thesupporting member 25 can be easily and accurately finished by cutting.

Infrared sensor 10 detects the infrared radiation emitted by thetemperature-measured object and converged by the light guide tube 24,and also detects the thermal radiation from the light guide tube 24itself. The second infrared sensor 11 detects the thermal radiation fromthe reference cavity 26 itself because the top-end of the referencecavity 26 is sealed. In addition, the second infrared sensor 11 isprovided close to the first infrared sensor 10 so as to haveapproximately the same temperature as the first infrared sensor 10. Thetemperature sensitive sensor 12 is a sensor which allows for measuringthe temperature of the first infrared sensor 10 and the second infraredsensor 11. Therefore the temperature sensitive sensor 12 is preferablyfixed to the bottom surface of the first infrared sensor 10 or thesecond infrared sensor 11, for example, by adhesive 12a. An adhesive ofhigh thermal conductivity may be preferably selected (for example,silicone of high thermal conductivity) for the adhesive 12a.

Furthermore, in this embodiment, the first infrared sensor 10 and thesecond infrared sensor 11 are sealed with the cover 21 which adheres thewindow member with low melting-point glass to receive infrared radiationthrough the windows 22 and 23. The windows 22 and 23 are made frombarium fluoride (BaF₂) or silicon (Si) with anti-reflection coating (ARcoating). Nitrogen gas is sealed in the space enclosed with the cover 21to prevent the first infrared sensor 10 and the second infrared sensor11 from deteriorating.

It is to be understood that the operation of the radiation clinicalthermometer of this embodiment is the same as the first embodiment shownin FIG. 1 and, for this reason, an explanation is omitted here.

FIG. 6 is a partially cut-out cross-section view showing the probe ofthe fourth embodiment of the radiation clinical thermometer inaccordance with the present invention.

The material of the probe 2 is, for example, ABS resin, and the probe 2is provided inside with the light guide tube 24 and supporting member21.

The light guide tube 24 is a pipe to efficiently converge the thermalradiation from the eardrum the temperature of which is to be measured,is made of metal such as copper, brass, or stainless steel, and has aninner surface which is mirror-finished and coated with gold (Au) toincrease the reflectivity.

The probe 2 is provided on the top-end thereof with the filter 7 havingtransmission wavelength characteristics. The filter 7, a dustproofwindow member for transmitting infrared radiation, is formed by opticalcrystal such as silicon (Si) or barium fluoride (BaF₂), or a polymersuch as polyethylene, and selectively transmits infrared-wavelengthradiation.

The supporting member 27, which is a member for supporting the lightguide tube 24 inside the probe 2, has the shape shown in FIG. 6 to formthe reference cavity 28 which serves as the light guide tube 9 in FIG.11. The supporting member 21 is a member of high thermal conductivity,the material of which is, for example, aluminum. The reference cavity 28of this embodiment comprises the supporting member 27 and the outer wallof the light guide tube 24, and the reference cavity 28 is sealed at theone end thereof (on the side of filter 7) so as to prevent infraredradiation from coming in from the temperature-measured object.Additionally, the outer wall of the light guide tube 24 constitutes apart of the reference cavity 28, so that the inner wall of the referencecavity 28 has approximately the same temperature as the inner wall ofthe light guide tube 24. The condition required for the reference cavity28 is to reach almost the same temperature as the light guide tube 24but is not always necessarily the same in material or inner surfacecondition. Furthermore the reference cavity 28 is so constructed as tobe tapered toward the filter 7 from the second infrared sensor 11.

Infrared sensor 10 detects the infrared radiation emitted by thetemperature-measured object and converged by the light guide tube 24,and detects the thermal radiation from the light guide tube 24 itself.The second infrared sensor 11 detects the thermal radiation from thereference cavity 28 itself because the top-end of the reference cavity28 is sealed. In addition, the second infrared sensor 11 is providedclose to the first infrared sensor 10 so as to have approximately thesame temperature as the first infrared sensor 10. The temperaturesensitive sensor 12 is a sensor which allows for measuring thetemperature of the first infrared sensor 10 and the second infraredsensor 11. Therefore the temperature sensitive sensor 12 is preferablyfixed to the bottom surface of the first infrared sensor 10 or thesecond infrared sensor 11, for example, by adhesive 12a. An adhesive ofhigh thermal conductivity may be preferably selected (for example,silicone of high thermal conductivity) as the adhesive 12a.

Furthermore, in this embodiment, unlike the embodiment shown in FIG. 5,the first infrared sensor 10 and the second infrared sensor 11 are notbuilt in one piece. That is, the first infrared sensor 10 is coveredwith a cover 29 having a window 30; the second infrared sensor 11 iscovered with a cover 31 having a window 32; the covers 29 and 31 aresealed with silicone of high thermal conductivity; the windows 30 and 32are made from barium fluoride (BaF₂) or silicon (Si) withanti-reflection coating (AR coating); and nitrogen gas is sealed in thespace enclosed with the covers 29 and 31 to prevent the first infraredsensor 10 and the second infrared sensor 11 from deteriorating. As longas the first infrared sensor 10 and the second infrared sensor 11 haveapproximately the same temperature, the first infrared sensor 10 and thesecond infrared sensor 11 are not necessarily made in one piece but maybe made separate, and also the angles of the first infrared sensor 10and the second infrared sensor 11 may differ.

It is to be understood that the operation of the radiation clinicalthermometer of this embodiment is the same as the first embodiment shownin FIG. 1 and, therefore, an explanation is omitted here.

FIG. 7 is a partially cut-out cross-section view showing the probe ofthe fifth embodiment of the radiation clinical thermometer in accordancewith the present invention.

The material of the probe 2 is, for example, ABS resin, and the probe 2is provided inside with the supporting member 33.

The supporting member 33 is provided on the top-end thereof with thefilter 7 having transmission wavelength characteristics The filter 7, adustproof window member for transmitting infrared radiation, is formedby optical crystal such as silicon (Si) or barium fluoride (BaF₂), or apolymer such as polyethylene, and selectively transmitsinfrared-wavelength radiation.

The supporting member 33 has the shape shown in FIG. 7 so as to form thelight guide hole 34 which serves as the light guide tube 8 shown in FIG.11 and so as to form the reference cavity 35 which serves as the lightguide tube 9 shown in FIG. 11. The material of the supporting member 33is, for example, aluminum or plastic and, in the case of plastic, one ofhigh thermal conductivity may be preferably selected. The inner surfaceof the light guide hole 34 is a mirror-finished surface coated with gold(Au) to increase the reflectivity. To treat the surface with gold,nickel may be coated before gold to the original surface, or gold may bedirectly deposited on the plastic surface. The reference cavity 35 issealed at the one end thereof (on the side of filter 7) so as to preventinfrared radiation from coming in from the temperature-measured object.Additionally, the reference cavity 35 is provided close to the lightguide hole 34 so as to have approximately the same temperature as thelight guide hole 34. The reference cavity 35 reaches approximately thesame temperature as the light guide hole 34 but is not alwaysnecessarily the same in material or inner surface condition. Furthermorethe reference cavity 35 is so constructed as to be tapered toward thefilter 7 from the second infrared sensor 11.

Infrared sensor 10 detects the infrared radiation emitted by thetemperature-measured object and converged by the light guide hole 34,and also detects the thermal radiation from the light guide hole 34itself. The second infrared sensor 11 detects the thermal radiation fromthe reference cavity 35 itself because the top-end of the referencecavity 35 is sealed. In addition, the second infrared sensor 11 isprovided close to the first infrared sensor 10 so as to haveapproximately the same temperature as the first infrared sensor 10. Thetemperature sensitive sensor 12 is a sensor which allows for measuringthe temperature of the first infrared sensor 10 and the second infraredsensor 11. Therefore the temperature sensitive sensor 12 is preferablyfixed to the bottom surface of the first infrared sensor 10 or thesecond infrared sensor 11, for example, by adhesive 12a. An adhesive ofhigh thermal conductivity may be preferably selected (for example,silicone of high thermal conductivity) as the adhesive 12a.

It is to be understood that the operation of the radiation clinicalthermometer of this embodiment is the same as the first embodiment shownin FIG. 1 and, therefore, an explanation is omitted here.

FIG. 8 is a partially cut-out cross-section view showing the probe ofthe sixth embodiment of the radiation clinical thermometer in accordancewith the present invention.

The material of the probe 2 is, for example, ABS resin, and the probe 2is provided inside with the supporting member 36.

The supporting member 36 is provided on the top-end thereof with thefilter 7 having transmission wavelength characteristics The filter 7, adustproof window member for transmitting infrared radiation, is formedby optical crystal such as silicon (Si) or barium fluoride (BaF₂), or apolymer such as polyethylene, and selectively transmitsinfrared-wavelength radiation.

The supporting member 36 has the shape shown in FIG. 8 so as to form thelight guide hole 37 as a light guide means which serves as the lightguide tube 8 shown in FIG. 11 and so as to form the reference cavity 38which serves as the light guide tube 9 shown in FIG. 11. The material ofthe supporting-member 36 is, for example, aluminum or plastic and, inthe case of plastic, one of high thermal conductivity may be preferablyselected. The inner surface of the light guide hole 37 is amirror-finished surface coated with gold (Au) to increase thereflectivity. To treat the surface with gold, nickel may be coatedbefore gold to the original surface, or gold may be directly depositedon the plastic surface. The reference cavity 38 is sealed at the one endthereof (on the side of filter 7) so as to prevent infrared radiationfrom coming in from the temperature-measured object. Additionally, thereference cavity 38 is provided close to the light guide hole 37 so asto have approximately the same temperature as the light guide hole 37.The reference cavity 38 reaches approximately the same temperature asthe light guide hole 37 but is not always necessarily the same inmaterial or inner surface condition. Furthermore the reference cavity 38is so constructed as to be tapered toward the filter 7 side from thesecond infrared sensor 11 side.

Additionally, in this embodiment, the light guide hole 37 is soconstructed as to be tapered toward the filter 7 from the first infraredsensor 10. It may be considered reasonable that a small emission inletfor the infrared radiation from the temperature-measured object causesthe incident energy received by the first infrared sensor 10 todecrease, however, the incident energy is never made small according tothis embodiment. This is explained below.

When the light guide hole 37 becomes smaller, the infrared radiationfrom the temperature-measured object reaches the infrared sensor 10 byreflecting more frequently inside the light guide hole 37, and thus theincident energy is attenuated. In this embodiment, the reflectivecoefficient of the light guide hole 37 is made extremely close to 1,whereby an increase in the number of reflections inside the light guidehole 37 may not cause energy attenuation due to reflection.Additionally, in the case where the inner surface of the light guidehole 37 is a perfect reflector, the incident energy to be received bythe first infrared sensor depends on the size of the emission outlet ofthe light guide hole 37 which determines the view of the infraredsensor. Generally narrowing the view tends to result in a decrease inthe incident energy. As shown in FIG. 8, the incident energy neverdecreases unless the emission outlet of the light guide hole 37 is madesmaller, and thus sensitivity is never deteriorated.

Turning to FIG. 8, infrared sensor 10 detects the infrared radiationemitted by the temperature-measured object and converged by the lightguide hole 37, and also, detects the thermal radiation from the lightguide hole 37 itself. The second infrared sensor 11 detects the thermalradiation from the reference cavity 38 itself because the top-end of thereference cavity 38 is sealed. In addition, the second infrared sensor11 is provided close to the first infrared sensor 10 so as to haveapproximately the same temperature as the first infrared sensor 10. Thetemperature sensitive sensor 12 is a sensor which allows for measuringthe temperature of the first infrared sensor 10 and the second infraredsensor 11. Therefore the temperature sensitive sensor 12 is preferablyfixed to the bottom surface of the first infrared sensor 10 or thesecond infrared sensor 11, for example, by adhesive 12a. An adhesive ofhigh thermal conductivity may be preferably selected (for example,silicone of high thermal conductivity) as the adhesive 12a.

It is to be understood that the operation of the radiation clinicalthermometer of this embodiment is the same as the first embodiment shownin FIG. 1 and, therefore, an explanation is omitted here.

In this embodiment, when the supporting member 36 is provided with thelight guide hole 37, the light guide hole 37 tapers from the firstinfrared sensor 10 side towards the filter 7 side. However, the presentinvention is not limited thereto. When a light guide tube is used, thelight guide tube tapers toward the filter 7 side from the first infraredsensor 10 side. In this case, the light guide tube may be made frommetal such as copper, brass, or stainless steel, and also from plasticas other material by depositing gold on to a plastic film having mirrorsurface and then forming a cone of the film to use the cone as the lightguide tube.

Furthermore, in this embodiment, both the reference cavity 38 and thelight guide hole 37 are so constructed as to be tapered toward thefilter 7 side from the first infrared sensor 10 or the second infraredsensor 11, to which the present invention is not limited, however, onlythe light guide hole 37 may be so constructed as to be tapered towardthe filter 7 from the first infrared sensor 10.

In each embodiment explained above the reference cavity of thesupporting member is formed by die-casting. However the presentinvention is not limited thereto and the reference cavity may forexample be formed by cutting. In this case the reference cavity is notalways necessarily to be tapered continuously smooth but it issufficient that the area of the emission inlet is smaller than the areaof the emission outlet. For example, as shown in FIG. 9, the supportingmember 39 may be tapered stepwise when the reference cavity 40 isformed. Even in this case, it still remains unchanged that the referencecavity 40 is so constructed as to be tapered off toward the emissioninlet of the light guide means from the second infrared sensor side.

TECHNICAL AVAILABILITY OF THE INVENTION

The present invention is disclosed for a radiation clinical thermometer,however, it may be applied generally to a radiation thermometer.

What is claimed is:
 1. A radiation clinical thermometer comprising aprobe; a light guide means which is provided with an emission inlet andan emission outlet to guide the infrared radiation from thetemperature-measured object; a first infrared sensor for detecting theinfrared radiation from the light guide means; a temperature sensitivesensor which generates a reference temperature signal; a referencecavity which indicates approximately the same temperature condition assaid light guide means and is sealed so as to shut out infraredradiation from outside; a second infrared sensor for detecting theinfrared radiation from the reference cavity; a temperature computingmeans for calculating temperature in accordance with the signals fromsaid first infrared sensor, said second infrared sensor, and saidtemperature sensitive sensor; and a display unit for displayingtemperature in accordance with the signal from the temperature computingmeans; wherein the probe is provided on the inside thereof with saidlight guide means and said reference cavity, at least either said lightguide means or said reference cavity being tapered off toward theemission inlet from said first or second infrared sensor side.
 2. Theradiation clinical thermometer set forth in claim 1 characterized inthat said light guide means comprises a pipe and said reference cavitycomprises a supporting member which also supports said pipe.
 3. Theradiation clinical thermometer set forth in claim 2 characterized inthat said supporting member is made of a material with high thermalconductivity.
 4. The radiation clinical thermometer set forth in claim 3characterized in that said member of high thermal conductivity is madeof aluminum.
 5. The radiation clinical thermometer set forth in claim 2characterized in that said first infrared sensor and said secondinfrared sensor are arranged in parallel to each other across the centerof said probe, and the emission inlet of said pipe is positionedapproximately at the center of said probe and the emission outlet ispositioned toward said first infrared sensor, whereby the pipe ispositioned diagonally against the center line of said probe.
 6. Theradiation clinical thermometer set forth in claim 2 characterized inthat said first infrared sensor is positioned on the center line of saidprobe and said pipe is positioned along said center line.
 7. Theradiation clinical thermometer set forth in claim 2 characterized inthat a window member for transmitting infrared radiation is fitted tosaid pipe so as to seal the emission inlet of said light guide means. 8.The radiation clinical thermometer set forth in claim 2 characterized inthat a window member for transmitting infrared radiation is fitted tosaid supporting member so as to seal the emission inlet of said lightguide means.
 9. The radiation clinical thermometer set forth in claim 1characterized in that said light guide means comprises a pipe and saidreference cavity comprises the outer wall of said pipe and thesupporting member which supports said pipe.
 10. The radiation clinicalthermometer set forth in claim 1 characterized in that said light guidemeans and said reference cavity are formed into the same member in onepiece.
 11. The radiation clinical thermometer set forth in claim 1characterized in that said temperature sensitive sensor is adhered tothe bottom surface of said first infrared sensor or second infraredsensor by an adhesive.
 12. The radiation clinical thermometer set forthin claim 1 characterized in that a window member for transmittinginfrared radiation is fitted to said probe so as to seal the emissioninlet of said light guide means.